Thursday, July 9, 2015

[Paleontology • 2015] Wendiceratops pinhornensis • A Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation

Wendiceratops pinhornensis
   Evans & Ryan, 2015  
discovered bones in orange || doi: 10.1371/journal.pone.0130007

The fossil record of ceratopsid dinosaurs between the occurrence of their proximate sister taxa in the Turonian and the beginning of their well-documented radiation from the late Campanian of North America onwards (approximately 90 and 77 Ma) is poor, with only seven taxa described from this early period in their evolution. We describe a new taxon of a highly adorned basal centrosaurine, Wendiceratops pinhornensis gen. et sp. nov., from the lower part of the Oldman Formation (middle Campanian, approximately 78-79 Ma), Alberta, Canada. Over 200 bones derived from virtually all parts of the skeleton, including multiple well-preserved specimens of the diagnostic parietosquamosal frill, were collected from a medium-density monodominant bonebed, making the new taxon one of the best-represented early ceratopsids. The new taxon is apomorphic in having epiparietals at loci 2 and 3 developed as broad-based, pachyostotic processes that are strongly procurved anterodorsally to overhang the posterior and lateral parietal rami, and an ischium with a broad, rectangular distal terminus. Although the morphology of the nasal is incompletely known, Wendiceratops is inferred to have a large, upright nasal horn located close to the orbits, which represents the oldest occurrence of this feature in Ceratopsia. Given the phylogenetic position of the new taxon within Centrosaurinae, a enlarged nasal horn is hypothesized to have arisen independently at least twice in ceratopsid evolution.

Fig 3. Skeletal reconstruction of Wendiceratops pinhornensis gen. et sp. nov.
Elements represented in the material collected from the bonebed are indicated in blue.

Systematic Palaeontology

Dinosauria Owen, 1842 
Ornithischia Seeley, 1887 

Ceratopsia Marsh, 1890 
Neoceratopsia Sereno, 1986 

Ceratopsidae Marsh, 1888 
Centrosaurinae Lambe, 1915 

Wendiceratops gen. nov.​335-BFFC-701E2C8B4DB3

Diagnosis: Monotypic, as for species.

Wendiceratops pinhornensis, gen. et. sp. nov.​89D-8F2D-FE53FC08A175

Etymology: The generic name honors Wendy Sloboda, who discovered the type locality, combined with ceratops (horned-face) from the Greek, a common suffix for horned dinosaur generic names. The specific epithet refers to the Pinhorn Provincial Grazing Reserve in Alberta, Canada, where the type locality is located.

Holotype: TMP 2011.051.0009, an incomplete parietal lacking the midline bar and left ramus.

Locality, horizon and age: The type locality occurs within the boundaries of the Pinhorn Provincial Grazing Reserve, south of the Milk River, County of Forty Mile No.8, Alberta, Canada.

Fig 2. Quarry map for the South Side Ceratopsian bonebed.
This bonebed has produced all of the known Wendiceratops pinhornensis gen. et sp. nov. material to date. Elements outlined in gray were collected in 2011 and their positions are approximate relative to the more precisely mapped bones collected in 2013 and 2014 (outlined in black). Inset rose diagram denotes a slight NE-SW trend in long axis orientation for the elements over 100 mm in length. See text for comments on the taphonomy of the bonebed.

Fig 16. Life reconstruction of Wendiceratops pinhornensis gen. et sp. nov.
 Illustration by Danielle Dufault. 

David C. Evans and Michael J. Ryan. 2015. Cranial Anatomy of Wendiceratops pinhornensis gen. et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE. 10(7): e0130007. doi: 10.1371/journal.pone.0130007

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